Vibration actuator and driving device for vibration actuator

Abstract

To provide a vibration actuator capable of reducing differences in vibration phases and vibration amplitudes at low voltage when driving a contact body using multiple vibrating bodies.SOLUTION: A vibrating actuator includes a vibrating body unit and a contact body that move relative to each other. The vibrating body unit includes multiple transformers in which a primary coil is connected in series and a vibrating body connected in parallel to each secondary coil of the transformers.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vibration actuator and a drive device for the vibration actuator. [Background technology]

[0002] Conventionally, a mechanism for driving a contact body using a plurality of vibrating bodies has been known. The plurality of vibrating bodies use electromechanical energy conversion elements such as piezoelectric elements and electrostrictive elements, and are driven by a common driving circuit. This reduces the circuit scale compared to a case in which an individual driving circuit is provided for each of the plurality of vibrating bodies. As a related technique, a vibration type driving device has been proposed in which a vibrator is connected in parallel to the secondary side of a step-up transformer (see Patent Document 1). Also, a driving device has been proposed in which two piezoelectric elements arranged in a straight line drive a single flat movable body (see Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-233399 A [Patent Document 2] JP 2008-278712 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the vibration type driving device of Patent Document 1, multiple vibrators are connected in parallel. In this case, the current flowing through each vibrator changes due to the difference in the resonance frequency and load of each vibrator, so the difference in vibration amplitude and vibration phase between each vibrator becomes large. Therefore, when one contact body is driven by multiple vibrators connected in parallel, sliding loss occurs due to the difference in vibration amplitude and vibration phase, and the driving efficiency of the contact body decreases.

[0005] In the driving device of Patent Document 2, two piezoelectric elements are electrically connected in series. In this case, the difference in current flowing through each piezoelectric element is smaller than when the two piezoelectric elements are connected in parallel. As a result, the difference in vibration phase is smaller, but the difference in vibration amplitude is larger depending on the difference in resonance frequency and load of each piezoelectric element. And when each piezoelectric element is connected in series, the voltage across both ends of each piezoelectric element connected in series becomes high voltage.

[0006] An object of the present invention is to provide a vibration actuator and a driving device for a vibration actuator that can reduce differences in vibration phase and vibration amplitude at a low voltage when driving a contact body using multiple vibrators. [Means for solving the problem]

[0007] In order to achieve the above object, a vibration actuator of the present invention is a vibration actuator including a vibration body unit and a contact body, the vibration body unit including a first vibration body having a first electro-mechanical energy conversion element and a first elastic body, a second vibration body having a second electro-mechanical energy conversion element and a second elastic body, a first transformer to which the first vibrating body is connected, and a second transformer to which the second vibrating body is connected; At least a primary coil of the first transformer and a primary coil of the second transformer are connected in series, and the first vibrating body and the second vibrating body are connected in parallel to the secondary coil of the first transformer and the secondary coil of the second transformer, respectively; The first elastic body and the second elastic body are arranged at a distance from each other, the first vibrating body and the second vibrating body are in contact with a common contact body, and the vibration of the first vibrating body and the second vibrating body causes relative movement between the vibrating body unit and the contact body. Effect of the Invention

[0008] According to the present invention, when a contact body is driven by a plurality of vibrators, differences in vibration phase and vibration amplitude can be reduced at a low voltage. [Brief description of the drawings]

[0009] [Figure 1] 2 is a diagram showing an example of a configuration of a vibration body unit according to the first embodiment. FIG. [Diagram 2] FIG. 1 is a diagram showing an example of the configuration of a conventional vibrating body unit. [Diagram 3] FIG. 3 is a diagram showing vibration amplitude characteristics versus frequency corresponding to the configuration of FIG. 2. [Figure 4] 2 is a diagram showing the oscillation amplitude of a current versus the frequency of an AC voltage applied to the series circuit of FIG. 1. [Diagram 5] 1A and 1B are diagrams showing the structure and electrical connection relationship of a vibration actuator that rotates a cylindrical shaft. [Figure 6] 13 is a diagram showing the relationship between the amplitude of an AC voltage applied to each vibrator and the rotation angle when a cylindrical shaft is rotationally driven. FIG. [Figure 7] FIG. 2 is a diagram illustrating a first example of a drive circuit for the vibration actuator according to the first embodiment. [Figure 8] FIG. 1 is a diagram showing an example of a vibration type actuator according to a first embodiment. [Figure 9] 11 is a diagram showing the mounting phase of each vibrator unit with respect to a cylindrical shaft. FIG. [Figure 10] FIG. 4 is a diagram showing a second example of the drive circuit of the vibration actuator according to the first embodiment. [Figure 11] 11A and 11B are diagrams illustrating an example of a vibration type actuator according to a second embodiment. [Figure 12] 11 is a diagram showing an example of the configuration of a vibration actuator according to a second embodiment. FIG. [Figure 13] FIG. 2 is a diagram showing an electrode structure of a circular ring-shaped piezoelectric body. [Figure 14] FIG. 2 is a diagram showing a wiring structure of a piezoelectric body. [Figure 15] FIG. 11 is a diagram illustrating a first example of a drive circuit for a vibration actuator according to a second embodiment. [Figure 16] 13A to 13C are diagrams illustrating the configuration and vibration modes of a vibrating body according to a third embodiment. [Figure 17] 13A and 13B are diagrams illustrating an example of a vibration type actuator according to a third embodiment. [Figure 18] FIG. 11 is a diagram showing an example of a drive circuit for a vibration actuator according to a third embodiment. [Figure 19] 13A and 13B are diagrams illustrating a first example of a linear vibration actuator according to a third embodiment. [Figure 20] 13A and 13B are diagrams illustrating a second example of a linear vibration actuator according to the third embodiment. [Figure 21] 13A and 13B are diagrams illustrating a first example of a vibration actuator according to a fourth embodiment. [Figure 22] FIG. 13 is a diagram illustrating a first example of a drive circuit for a vibration actuator according to a fourth embodiment. [Figure 23] 13 is a diagram showing vibration characteristics of each vibrating body unit of the fourth embodiment. FIG. [Figure 24] FIG. 13 is a diagram showing a second example of a drive circuit for the vibration actuator according to the fourth embodiment. [Diagram 25] 13A and 13B are diagrams illustrating a second example of the vibration actuator according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. However, the configurations described in the following embodiments are merely examples, and the scope of the present invention is not limited to the configurations described in the embodiments.

[0011] First Embodiment FIG. 1 is a diagram showing an example of the configuration of a vibrating body unit 10 according to the first embodiment. The vibrating body unit 10 comes into contact with a contact body and moves relative to each other. As a result, the vibrating body unit 10 drives the contact body. The vibrating body unit 10 in FIG. 1(a) has three vibrating bodies 1, 2, and 3, and transformers 5, 6, and 7. A piezoelectric body, an electrostrictive element, or the like, which is an electric-mechanical energy conversion means for exciting vibration, is joined to the vibrating bodies 1, 2, and 3. The vibrating body 1 is connected in parallel to the secondary coil of the transformer 5. The vibrating body 2 is connected in parallel to the secondary coil of the transformer 6. The vibrating body 3 is connected in parallel to the secondary coil of the transformer 7. The primary coil of the transformer 5, the primary coil of the transformer 6, and the primary coil of the transformer 7 are connected in series.

[0012] FIG. 1(b) is an equivalent circuit diagram of the vibrating body unit 10 of FIG. 1(a) in the case of using an ideal transformer with a winding ratio of "1" for each transformer. In this embodiment, a case where a piezoelectric body is bonded to the vibrating bodies 1, 2, and 3 will be described, but the vibrating bodies 1, 2, and 3 themselves may be constructed of a piezoelectric body. The piezoelectric body may also be a laminated piezoelectric body. In the following description, a piezoelectric body is bonded to each vibrating body. The number of vibrating bodies and the number of inductors of the vibrating body unit 10 are not limited to three. As shown in the equivalent circuit diagram of FIG. 1(b), the vibrating bodies 1, 2, and 3 are equivalently connected in series via a transformer.

[0013] Next, an example of a conventional vibrating body unit will be described. FIG. 2 is a diagram showing an example of the configuration of a conventional vibrating body unit. FIG. 2(a) is a diagram showing a configuration in which three vibrating bodies 1, 2, and 3 to which a piezoelectric body is bonded are connected in series. When an AC voltage with a frequency close to the resonant frequency is applied to the vibrating bodies 1, 2, and 3 electrically connected in series, vibrations are excited in the vibrating bodies 1, 2, and 3. The vibrating bodies 1, 2, and 3 are in pressure contact with the contact body, and a thrust is generated at the contact portion between the contact body and the vibrating body by the vibration generated in the vibrating body, and the contact body is driven. By electrically connecting multiple vibrating bodies in series, the thrust force against the contact body can be increased, and the difference in vibration of each vibrating body can be reduced. In other words, compared to the case where multiple vibrating bodies are connected in parallel, the case where multiple vibrating bodies are connected in series makes it easier to align the inflow current and vibration of each vibrating body even if there is a difference in the resonant frequency or load of each vibrating body.

[0014] However, as the number of vibrating bodies connected in series increases, the amplitude of the AC voltage required to vibrate the vibrating bodies increases. Therefore, when the number of vibrating bodies connected in series is large, the AC voltage applied to both ends of the multiple vibrating bodies connected in series (both ends of the series connection) as shown in FIG. 2(a) becomes high, and high voltage measures are required. For example, when AC voltages with amplitudes of V1, V2, and V3 are applied to vibrating bodies 1, 2, and 3 in FIG. 2(a), respectively, an AC voltage with an amplitude of approximately "Vo=V1+V2+V3" is applied to both ends of the series connection. Therefore, as the number of vibrating bodies connected in series increases, the AC voltage Vo becomes large.

[0015] In this embodiment, as shown in FIG. 1(a), the vibrating bodies 1, 2, and 3 are connected in parallel to the secondary coils of the transformers 5, 6, and 7. The vibrating bodies 1, 2, and 3 are electrically insulated from each other. The primary coils of the transformers 5, 6, and 7 are connected in series, and both ends of the series connection of the primary coils of the transformers 5, 6, and 7 are input terminals for AC voltage. Therefore, even if the vibrating bodies 1, 2, and 3 are not directly connected to each other as shown in FIG. 1(a), an AC voltage equivalent to that in the case of series connection can be applied to each vibrating body. Furthermore, since the vibrating bodies 1, 2, and 3 are not directly connected to each other, the AC voltages applied to each vibrating body are not added as described above. As shown in FIG. 1, the terminal voltage of the secondary coil of the transformer 5 is V1, the terminal voltage of the secondary coil of the transformer 6 is V2, and the terminal voltage of the secondary coil of the transformer 7 is V3. Because vibrating body 1, vibrating body 2, and vibrating body 3 are not directly connected, an AC voltage equal to or greater than terminal voltage V1 is not applied to vibrating body 1. Similarly, an AC voltage equal to or greater than terminal voltage V2 is not applied to vibrating body 2, and an AC voltage equal to or greater than terminal voltage V3 is not applied to vibrating body 3.

[0016] On the other hand, since the transformers 5, 6, and 7 are connected in series, the AC voltages are added. When the winding ratio of each transformer is 1:N, the terminal voltage of the primary coil of the transformers 5, 6, and 7 is the value obtained by dividing the terminal voltage of the secondary coil by N. Therefore, the AC voltage across the series connection of the transformers 5, 6, and 7 is "(V1+V2+V3) / N". However, "N>1". This allows the AC voltage applied to the vibrating body unit 10 to be lower than that in the case of FIG. 2(a). In the above description, the winding ratio of all the transformers is 1:N, but the winding ratio of some or all of the transformers may be different. In this case, the ratio of the vibration speeds of the vibrating bodies 1, 2, and 3 can be changed. This point will be described in detail later.

[0017] FIG. 2(b) is an equivalent circuit diagram of FIG. 2(a). The circuit consisting of C0, L1, C1, and R1 represents the equivalent circuit of the vibrating body 1. The circuit consisting of C0, L2, C2, and R2 represents the equivalent circuit of the vibrating body 2. The circuit consisting of C0, L3, C3, and R3 represents the equivalent circuit of the vibrating body 3. The damping capacitance C0 of each equivalent circuit represents the electrical characteristics of the piezoelectric body joined to the vibrating bodies 1, 2, and 3. The series resonant circuit consisting of Lx, Cx, and Rx (x is an integer from 1 to 3) represents the mechanical characteristics of the vibrating bodies 1, 2, and 3. IE1, IE2, and IE3 are the values ​​of the current flowing through the damping capacitance C0 of the vibrating bodies 1, 2, and 3, respectively, and IM1, IM2, and IM3 are the values ​​of the current flowing through the series resonant circuits Lx, Cx, and Rx of the vibrating bodies 1, 2, and 3, respectively. Then, the value of the current Io becomes equal to "IE1+IM1", "IE2+IM2" and "IE3+IM3".

[0018] FIG. 3(a) is a diagram showing the vibration amplitude characteristics with respect to frequency when an AC voltage is applied to each of the vibrating bodies 1, 2, and 3. The vibrating bodies 1, 2, and 3 have vibration characteristics with maximum amplitudes at different resonant frequencies Fr1, Fr2, and Fr3. FIG. 3(b) is a diagram showing the vibration amplitudes of currents IM1 (dash line), IM2 (solid line), IM3 (dashed line), and current Io (dotted line) with respect to the frequency of the AC voltage applied to the series resonant circuit of Lx, Cx, and Rx in FIG. 2(b). As shown in FIG. 3(b), when an AC voltage is applied to the series resonant circuit of Lx, Cx, and Rx in FIG. 2(b), the currents IM1, IM2, and IM3 representing the vibration velocities of the vibrating bodies 1, 2, and 3 have maximum amplitudes at the resonant frequency Fr0, but the maximum amplitudes of each current are different. If the maximum amplitudes of the currents of the vibrating bodies 1, 2, and 3 are different at the resonant frequency Fr0, differences occur in the vibration velocities of the vibrating bodies 1, 2, and 3. When a contact body is brought into pressure contact with the vibrating bodies 1, 2, and 3 to drive them while there is a difference in the vibration speeds of the vibrating bodies 1, 2, and 3, a difference occurs in the amount of slip at the contact portion of the contact body. When a difference occurs in the amount of slip, loss occurs that does not contribute to driving, and the driving efficiency of the contact body decreases. Also, as shown in FIG. 3(b), the change in the current Io flowing through the vibrating body unit 10 is significantly different from the change in the current IMx (x is an integer from 1 to 3). For this reason, it is difficult to accurately detect the magnitude of the current IMx by detecting the current Io.

[0019] Next, the equivalent circuit diagram of FIG. 1(b) will be described. In the equivalent circuit diagram of the vibrating bodies 1, 2, and 3, a series circuit consisting of a damping capacitance C0 and a series circuit Lx, Cx, and Rx (x is an integer from 1 to 3) is connected in parallel. In the equivalent circuit diagram of FIG. 1(b), inductors L01, L02, and L03, which show the equivalent circuit of a transformer, are added to the equivalent circuit diagram of FIG. 1(a). In the equivalent circuit diagram of FIG. 1(b), the vibrating bodies 1, 2, and 3 are connected in series via transformers 5, 6, and 7. Since the vibrating bodies 1, 2, and 3 are equivalently connected in series, the same current basically flows through the vibrating bodies 1, 2, and 3. L0x (x is an integer from 1 to 3) connected in parallel with the damping capacitance C0 resonates in parallel at a predetermined frequency.

[0020] Therefore, when focusing on the parallel circuit consisting of the inductor L0x and the damping capacitance C0, the magnitude of the current IEx' (x is an integer from 1 to 3) flowing through the parallel circuit approaches zero in the vicinity of the parallel resonance frequency. When the current IEx' becomes almost zero, "current IMx'+IEx'" (x is an integer from 1 to 3) becomes approximately equal to the current IMx'. Therefore, the current Io' flowing through the vibrating body unit 10 shown in FIG. 1(a) becomes approximately equal to the current IMx'.

[0021] FIG. 4 is a diagram showing the vibration amplitudes of currents IM1' (dash line), IM2' (solid line), IM3' (dashed line) and current Io' (dotted line) versus the frequency of the AC voltage applied to the series circuit of Lx, Cx and Rx in FIG. 1(b). The vibration amplitudes of currents IM1', IM2' and IM3' are approximately the same, and each has a maximum amplitude at the same resonance frequency Fr0'. The resonance frequency Fr0' is approximately the average frequency of Fr1 (resonance frequency of vibrating body 1), Fr2 (resonance frequency of vibrating body 2) and Fr3 (resonance frequency of vibrating body 3). In addition, the current Io' has approximately the same amplitude as the current IMx' in a frequency range above a certain amplitude.

[0022] As described above, the vibrator unit 10 in FIG. 1(a) employs a configuration in which the vibrators are connected in parallel to the secondary coils (inductors) of the multiple transformers, and the primary coils of the transformers are connected in series. This allows the vibration amplitudes and vibration phases of the vibrators 1, 2, and 3 to be aligned even when multiple vibrators are vibrated by one driving voltage. As a result, the thrust generated by each vibrator can be efficiently transmitted to one contact body. Furthermore, by employing the above configuration in the vibrator unit 10, the AC voltage applied to the vibrator unit 10 can be reduced as described above.

[0023] FIG. 5 is a diagram showing the structure and electrical connection relationship of a vibration actuator that rotates a cylindrical shaft. FIG. 5(a) is a diagram showing the structure of a vibration actuator that rotates a cylindrical shaft with three vibrators in contact with the outer periphery of the cylindrical shaft. Vibrators 1, 2, and 3 are vibrators that vibrate in the vertical direction (direction of the arrow). Cylindrical shaft 4 is an example of a contact body. Vibrators 1, 2, and 3 are evenly arranged on the outer periphery of cylindrical shaft 4 at 120° intervals. Vibrators 1, 2, and 3 are evenly pressed and contacted with cylindrical shaft 4 by a pressure mechanism (not shown). By exciting vibrations in the vertical direction by vibrating vibrators 1, 2, and 3, cylindrical shaft 4 rotates clockwise.

[0024] FIG. 5(b) is a diagram showing electrical connections in the vibrating body unit 10. The secondary coils of the transformers 5, 6, and 7 are connected in parallel to the piezoelectric bodies joined to the vibrating bodies 1, 2, and 3. The vibrating body unit 10 is provided with a connector 8 for inputting an AC voltage. The primary coils of the transformers 5, 6, and 7 are connected in series, and both ends of the series connection are connected to the connector 8. The vibrating bodies 1, 2, and 3 and the transformers 5, 6, and 7 are housed in a ring-shaped case 9, and these are integrated to form the vibrating body unit 10. In addition, the vibrating bodies 1, 2, and 3 have protrusions that are pressed into contact with the cylindrical shaft 4 at every 120° in the hollow cylindrical part through which the cylindrical shaft 4 of the case 9 passes, and are pressed against the cylindrical shaft 4 with a constant pressure force by a support member including a spring structure (not shown). In addition, the protrusion amount and pressure force of each protrusion can be adjusted by a rotary-linear conversion mechanism or the like provided in the case 9.

[0025] FIG. 6 is a diagram showing the relationship between the amplitude of the AC voltage applied to the vibrating bodies 1, 2, and 3 and the rotation angle when the cylindrical shaft 4 is rotated by applying an AC voltage to the vibrating body unit 10. Due to the load fluctuation caused by the eccentricity of the cylindrical shaft 4, one period of load fluctuation occurs in synchronization with the rotation of the cylindrical shaft 4. Therefore, when the load becomes heavy, the voltage amplitude of the AC voltage increases, and when the load becomes light, the voltage amplitude of the AC voltage decreases. Since the vibrating bodies 1, 2, and 3 are arranged at approximately equal intervals of approximately 120° on the outer periphery (circumference) of the cylindrical shaft 4, the three waveforms (waveforms showing the voltage amplitudes of the vibrating bodies 1, 2, and 3) in FIG. 6 show characteristics in which the rotation phase is shifted approximately every 120°. In addition, the average values ​​of the voltage amplitudes of the vibrating bodies 1, 2, and 3 during one rotation of the cylindrical shaft 4 are different from each other. This is mainly due to the internal loss and the difference in resonance frequency of the vibrating bodies 1, 2, and 3.

[0026] As described above, in the vibrating body unit 10 of this embodiment, the vibrating body is connected in parallel to each of the secondary coils of each transformer, and the primary coils of each transformer are connected in series. Therefore, the vibration amplitude and vibration phase of the vibrating bodies 1, 2, and 3 are aligned, so that the difference in vibration speed of each vibrating body can be reduced. As a result, even if a difference occurs in the resonant frequency or load of the vibrating bodies 1, 2, and 3, the vibration phase and vibration amplitude of the applied AC voltage are automatically adjusted, and the vibration speed of the vibrating bodies 1, 2, and 3 is aligned. As a result, the cylindrical shaft 4 as the contact body can be driven with high efficiency.

[0027] FIG. 7 is a diagram showing a first example of a drive circuit for a vibration actuator using the vibration body unit 10 according to the first embodiment. The drive circuit for the vibration actuator corresponds to a drive device for the vibration actuator. The drive circuit for the vibration actuator in FIG. 7 has a vibration body unit 10, a voltage generating section 13, a resistor 14, an amplitude detecting section 15, a comparing section 16, and a power supply control section 17. The vibration body unit 10 corresponds to the part surrounded by a dotted line in FIG. 7. In the vibration body unit 10, the primary coils of the transformers 5, 6, and 7 are connected in series. Moreover, the secondary coils of the transformers 5, 6, and 7 are connected in parallel to the vibration bodies 1, 2, and 3, respectively.

[0028] The inductance values ​​of the secondary coils of the transformers 5, 6, and 7 connected in parallel to the vibrating bodies 1, 2, and 3, respectively, are matched at a predetermined frequency close to the resonant frequency of the vibrating body unit 10 (a frequency within a predetermined range from the resonant frequency of the vibrating body unit 10, for example, within the resonant frequency ±10% of the resonant frequency). That is, when the matching frequency is F0, the damping capacity is C0, and the inductance value of the secondary coils of the transformers is L0, the relationship between the respective values ​​is expressed by Equation 1.

[0029]

number

[0030] The voltage generating unit 13 generates an AC voltage to be applied to the vibrating body unit 10. The resistor 14 is connected to the vibrating body unit 10 in order to measure the current flowing through the vibrating body unit 10. The resistor 14 outputs a voltage proportional to the vibration velocity of the vibrating bodies 1, 2, and 3. To be precise, the amplitude of the vibrating body is proportional to the value obtained by integrating the vibration velocity with respect to time, but since the amplitude of the vibration velocity is roughly proportional to the vibration amplitude, hereinafter it is assumed that the vibration amplitude is controlled by controlling the amplitude of the vibration velocity.

[0031] The amplitude detection unit 15 detects the amplitude of the AC voltage detected by the resistor 14. The comparison unit 16 compares the amplitude command from a vibration amplitude command means (not shown) with the amplitude of the AC voltage output by the amplitude detection unit 15, and outputs the comparison result to the power supply control unit 17. The power supply control unit 17 controls the voltage generation unit 13 based on the comparison result output by the comparison unit 16. The power supply control unit 17 controls the AC voltage output by the voltage generation unit 13 by outputting a command to control the frequency or amplitude of the AC voltage to the voltage generation unit 13. The current flowing through the vibration body unit 10 is approximately proportional to the vibration speed of the vibration bodies 1, 2, and 3 due to the effect of frequency matching of the transformers 5, 6, and 7. The resistor 14 detects the current flowing through the vibration body unit 10, and the power supply control unit 17 controls the AC voltage, so that the amplitude of the vibration bodies 1, 2, and 3 of the vibration body unit 10 can be stably and quickly controlled.

[0032] 7, a transformer is connected in parallel to each vibrating body, but a parallel circuit of a transformer and a capacitor may be connected in parallel to each vibrating body. By connecting a capacitor in parallel to each vibrating body in addition to the transformer, the matching frequency can be fine-tuned.

[0033] Next, a failure of the vibrating body unit 10 in this embodiment will be described. Even if a failure such as a short circuit or disconnection occurs in some of the vibrating bodies 1, 2, and 3, the vibrating body unit 10 can continue to drive the contact body because the primary coils of the transformers 5, 6, and 7 are connected in series. Even if some of the vibrating bodies 1, 2, and 3 in FIG. 7 are electrically shorted, AC voltage continues to be applied to the remaining vibrating bodies. Since the shorted vibrating body stops vibrating, the load becomes heavier, and the number of vibrating bodies connected in series equivalently decreases, and the thrust decreases. On the other hand, when the number of vibrating bodies decreases, the voltage applied to the remaining vibrating bodies increases, and feedback is automatically applied to maintain the thrust. This allows the drive control of the vibrating body unit 10 to continue.

[0034] Next, a case where a wire break occurs in the vibrator will be described. The connection between the piezoelectric body and the wiring may be broken due to the influence of vibration or the like. Even in this case, since the primary coils of each transformer are connected in series, AC voltage continues to be applied to the remaining vibrators where no wire break occurs. The broken vibrator stops, so the load becomes heavier, the number of vibrators that can be driven decreases, and the thrust decreases. In addition, if a wire break occurs between the piezoelectric body connected to the vibrator and the wiring, the secondary side of the transformer becomes in a high impedance state due to the wire break, and the primary voltage amplitude of the transformer where the connection is not broken increases, automatically increasing the excitation force for each vibrator. This allows the drive control of the vibrator unit 10 to continue.

[0035] When the above-mentioned short circuit or disconnection occurs inside the vibrator unit 10, the current flowing through the vibrator unit 10 increases compared to when no short circuit or disconnection occurs. The resistor 14 measures the current flowing through the vibrator unit 10. By detecting an increase in the current flowing through the resistor 14, it is possible to detect the occurrence of a fault such as a short circuit or disconnection. For example, when the increase in the current flowing through the resistor 14 is equal to or greater than a predetermined amount, the amplitude detector 15 may detect that a fault has occurred in the vibrator unit 10. Furthermore, an amplifier circuit may be provided on the output side of the voltage generator 13 to amplify the amplitude of the AC voltage applied to each vibrator.

[0036] FIG. 8 is a diagram showing an example of a vibration type actuator according to the first embodiment. FIG. 8(a) is a diagram showing an example of a vibration type actuator configured by connecting a vibration body unit 10 and a vibration body unit 11 in series. FIG. 8(b) is a diagram showing an example of a vibration type actuator configured by connecting a vibration body unit 10 and a vibration body unit 11 in parallel. The number of multiple vibration body units connected in series or in parallel is not limited to two. The vibration body unit 10 and the vibration body unit 11 have the same configuration. Each of the vibration body units 10 and 11 has three vibration bodies and three transformers built therein. The primary coils of the three transformers are connected in series, and a vibration body is connected in parallel to each of the three transformers. The number of vibration bodies and transformers built in the vibration body units 10 and 11 is not limited to three. Here, the three vibration bodies built in the vibration body units 10 and 11 have an average value of the resonance frequency within a predetermined frequency range.

[0037] An example of manufacturing the vibration body units 10 and 11 shown in FIG. 8 will be described. The vibration body units 10 and 11 can be manufactured manually or automatically. For example, when a certain number of vibration bodies (e.g., tens to hundreds) are manufactured, a list of resonance frequencies is created from the measurement results of the resonance frequencies of each vibration body. Next, based on the list of resonance frequencies, a certain number of vibration bodies are classified into classes according to several frequency ranges. For example, a certain number of vibration bodies are classified into 500 Hz classes. Then, three vibration bodies are randomly selected from the same class, and the average value of the resonance frequencies of the three vibration bodies is calculated. The random selection of the three vibration bodies is repeated until a combination of three vibration bodies whose average value of the resonance frequency falls within a frequency range (e.g., a predetermined frequency ±25 Hz) predetermined for each class is obtained. When three vibration bodies that fall within a frequency range predetermined for each class are obtained, the three vibration bodies constitute one vibration body unit.

[0038] Therefore, three vibrators whose average value of the resonant frequency falls within the above frequency range are incorporated into one vibrator unit. It is difficult to prepare many vibrators whose resonant frequencies are close to each other, but if the method of aligning the average value of the resonant frequencies of multiple vibrators is used as in this embodiment, a relatively large number of vibrators can be prepared. In addition, multiple vibrators whose resonant frequency variance falls within a predetermined variance range may be selected for one vibrator unit, instead of the average value of the resonant frequency. In this case, multiple vibrators whose resonant frequency variance falls within a predetermined variance range are incorporated into one vibrator unit. By setting the variance to a relatively large value, it is possible to prevent the resonant frequencies of the selected vibrators from being too uniform, thereby stabilizing the characteristics of the vibrator unit. As described above, by combining multiple vibrator units of the same class to form a vibration type actuator, a high-output and efficient vibration type actuator can be stably manufactured.

[0039] In the case of FIG. 8(a), two vibrating body units 10 and 11 are connected in series. When the number of vibrating body units connected in series increases, the amplitude of the AC voltage needs to be increased accordingly, and the applied voltage becomes high. When the applied voltage becomes high, the entire vibrating body unit becomes large due to insulation measures and the like. As a result, the cost also increases. Therefore, as shown in FIG. 8(b), a configuration in which each vibrating body unit 10 and 11 are connected in parallel can be adopted. In this case, since the two vibrating body units 10 and 11 are connected in parallel, it is possible to drive each vibrating body unit with an AC voltage with half the amplitude compared to the case in which the two vibrating body units 10 and 11 are connected in series. As described above, since the vibrating body units 10 and 11 are of the same class, the resonant frequencies of the vibrating body units (average value of the resonant frequencies of the incorporated vibrators) are approximately the same. In addition, since the three vibrating bodies are evenly arranged on the circumference of the cylindrical shaft 4, the loads of the three vibrating bodies are averaged. Therefore, the load fluctuation due to rotation is small. As a result, the difference in vibration speed between the vibrating body units can be reduced, and efficient driving can be achieved.

[0040] FIG. 9 is a diagram showing the mounting phases of the vibrating body units 10 and 11 with respect to the cylindrical shaft 4. The two vibrating body units are mounted with a rotation phase shift of 60°. As shown in FIG. 9, the vibrating body units 10 and 11 are evenly arranged on the circumference of the cylindrical shaft 4 with a predetermined phase shift, thereby realizing rotation of the cylindrical shaft with little torque fluctuation. The vibrating body units 10 and 11 each incorporate three transformers and three vibrators. Therefore, in each of the vibrating body units 10 and 11, the three vibrating bodies are arranged at 120° intervals. When the vibrating body units 10 and 11 have two vibrating bodies, it is preferable that the two vibrating bodies are arranged at 180° intervals. Furthermore, when the vibrating body unit has four vibrating bodies, it is preferable that the four vibrating bodies are arranged at 90° intervals.

[0041] FIG. 10 is a diagram showing a second example of a drive circuit of a vibration type actuator using the vibrating body unit 10 according to the first embodiment. In FIG. 10, the circuit surrounded by the dotted line shows the internal circuits of the vibrating body units 10 and 11. The vibrating body unit 10 and the vibrating body unit 11 have almost the same configuration and are connected in parallel as shown in FIG. 8(b). Each of the vibrating body units 10 and 11 has three transformers and three vibrators. The inductance value of the secondary coil of each transformer is matched at a predetermined frequency within the frequency range of the AC voltage output by the voltage generating unit 13. That is, if the matching frequency is F0, the damping capacity is C0, and the inductance value of the secondary coil of the transformer is L0, the relationship between the values ​​is expressed by the above-mentioned formula 1.

[0042] The voltage generating unit 13 generates an AC voltage to be applied to the vibrating body units 10 and 11. The resistor 14 is a resistor for measuring the sum of the currents flowing through the vibrating body units 10 and 11. The vibrating body units 10 and 11 have the same resonance frequency, and the vibrators evenly arranged on the circumference of the cylindrical shaft 4 are subjected to approximately the same average load. For this reason, no significant shift occurs in the phase of the inflow current. Therefore, the amplitude detecting unit 15 outputs a voltage that is approximately proportional to the sum of the amplitudes of the currents flowing through each of the vibrating body units 10 and 11. The comparing unit 16 then compares the sum of the amplitudes of the currents with an amplitude command from a command means (not shown), and the power supply control unit 17 controls the frequency or amplitude of the AC voltage output by the voltage generating unit 13 based on the comparison result.

[0043] In this embodiment, an example in which a plurality of vibration body units drive the same contact body has been described, but a plurality of vibration body units may each drive a different contact body. In this case, it is difficult to drive each contact body at exactly the same speed, but since a plurality of vibration bodies can be driven simultaneously at approximately the same vibration speed, it is possible to reduce the circuit scale. In addition, each vibration body unit may drive a contact body such as a conical shaft having a different diameter depending on the contact portion, as well as the outer periphery of a cylindrical shaft having the same diameter. In this case, the circumferential speed differs depending on the diameter of the portion where the vibration body unit and the contact body contact. Therefore, the ratio of the vibration speed of each vibration body of each vibration body unit can be set according to the speed ratio of the circumferential speed.

[0044] Here, the vibration speed of the vibrator changes in proportion to the inverse of the winding ratio of the transformer connected in parallel to the vibrator. For example, the vibration speed of the vibrator can be set to "1 / 2" by changing the winding ratio of the transformer from 1:N to 1:2×N. Therefore, the winding ratio of each transformer included in each of the multiple vibrator units connected in parallel or in series may be set according to the shape of the contact body. In this case, the winding ratio of each transformer of some or all of the multiple vibrator units may be set to different values. This allows each vibrator of the multiple vibrator units to drive the contact body at an appropriate vibration speed according to the shape of the contact body. In the above example, the winding ratio of each transformer included in one vibrator unit is set to the same value, and the value of the winding ratio of the transformer is set for each vibrator unit. In addition, the winding ratio of some or all of the transformers included in one vibrator unit may be set to different values ​​according to the shape of the contact body. In this case, some or all of the vibrators of one vibrator unit can be driven at different vibration speeds according to the shape of the contact body.

[0045] Moreover, each vibrator unit incorporates a plurality of vibrators. The plurality of vibrators may be the same or different. When some or all of the vibrators incorporated in the vibrator unit are different, it is preferable that the resonant frequencies of the vibrators are close (within a certain range). Furthermore, when the number of vibrators (vibrators connected in series in the equivalent circuit diagram) incorporated in the vibrator unit exceeds a predetermined number, there is a possibility that the vibrator unit will not operate normally with only the transformer in the vibrator unit. In this case, the voltage generating unit 13 may have a transformer that boosts the AC voltage of each phase.

[0046] <Second embodiment> Next, the second embodiment will be described. FIG. 11 is a diagram showing an example of a vibration actuator of the second embodiment. Three vibration actuators 18, 25, 28 of the shaft output each have one vibrator, and are connected by bevel gears to rotate on one shaft. The output shaft 19 is connected to the vibration actuator 18, the output shaft 26 is connected to the vibration actuator 25, and the output shaft 29 is connected to the vibration actuator 28. The bevel gear 20 is attached to the tip of the output shaft 19, the bevel gear 27 is attached to the tip of the output shaft 26, and the bevel gear 30 is attached to the tip of the output shaft 29. The bevel gears 20, 27, 30 are connected to bevel gears 31, which are one size larger and attached to a rotating shaft (not shown), at intervals of 120°.

[0047] The vibrators of the vibration actuators 18, 25, 28 are equivalently connected in series to form one vibrator unit, and AC voltages PA, PB, PNA, and PNB with a phase difference of 90° are applied to the driving voltage lines of the A phase, B phase, NA phase, and NB phase. This excites vibration, and drives the bevel gear 31 that is indirectly connected. FIG. 12 is a diagram showing an example of the configuration of the vibration actuator 18 according to the second embodiment. The vibration actuator 18 has a rotor 21, an elastic body 22, a piezoelectric body 23, and a friction member 24. The rotor 21 is joined to the output shaft 19 at the center, and is held rotatably together with the output shaft 19. The elastic body 22 is a conductive member having a comb-shaped protruding structure. The piezoelectric body 23 is bonded to the elastic body 22. The friction member 24 is bonded to the upper part of the protruding structure of the elastic body 22, and is selected so that the contact portion wears slowly and stably.

[0048] FIG. 13 is a diagram showing the electrode structure of the annular piezoelectric body 23. FIG. 13 shows the connection state between the electrodes on one side of the piezoelectric body 23 and the drive voltage lines of each phase (A phase, B phase, NA phase, NB phase). Reference numerals 32 to 35 in FIG. 13 indicate the front (or back) sides of the A phase, B phase, NA phase, and NB phase. FIG. 14 is a diagram showing the wiring structure of the piezoelectric body 23 as viewed from the side. The back electrode of the piezoelectric body 23 is a single electrode on the entire surface. The A phase and NA phase electrodes of the piezoelectric element 23 are connected to the secondary side of the transformer 53, and the B phase and NB phase electrodes are connected to the secondary side of the transformer 54. AC voltages PA and PNA are applied to the primary side of the transformer 53, and AC voltages PB and PNB are applied to the primary side of the transformer 54, with the AC voltages PA and PNA and the AC voltages PB and PNB being out of phase with each other by 180°. Here, the transformers 53 and 54 are not provided with a center tap on the secondary side, but a circuit configuration may be adopted in which a center tap is provided and the above GND is connected.

[0049] Fig. 15 is a diagram showing a first example of a driving circuit of the vibration type actuator of the second embodiment. In the vibration type actuator 18, as shown in Fig. 14, transformers 53 and 54 are connected to the piezoelectric body, and the vibration type actuators 25 and 28 are similarly connected. In addition, the primary coils of the transformers of the vibration type actuators 18, 25, and 28 are connected in series for each phase. In the example of Fig. 15, three vibration type actuators 18, 25, and 28 are connected in series to form one vibrator unit to which AC voltages PA, PB, PNA, and PNB are input as a whole, constituting the vibration type actuator 42. Each of the vibration type actuators 18, 25, and 28 shows an area surrounded by a dashed line, and the vibration type actuator 42 shows an area surrounded by a dotted line.

[0050] A known H-bridge circuit (power amplifier circuit) (not shown) is built into the A, NA terminals and the B, NB terminals of the voltage generating unit 41. The pulsed driving voltage output from the H-bridge circuit is waveform-shaped by a series resonant circuit consisting of inductors 37, 39 and capacitors 38, 40 inserted between the H-bridge circuit and the vibration actuator 42. The waveform-shaped pulsed driving voltage is then applied to the vibration actuator 42. The series resonant circuit consisting of the inductors 37, 39 and capacitors 38, 40 is matched and adjusted at a predetermined frequency within the driving frequency range of the vibration actuator 42. This prevents the driving voltage amplitude of the vibration actuator 42 from fluctuating significantly within the driving frequency range.

[0051] Resistors 14 and 36 for measuring current are connected to the current detection terminals of each H-bridge of the voltage generating unit 41. The resistors 14 and 36 measure a current corresponding to the vibration velocity of each vibrating body included in the vibration actuator 42. The amplitude detecting unit 15 detects the vibration velocity of the vibrating body based on the measurement values ​​of the resistors 14 and 36. The comparing unit 16 compares a vibration amplitude command from a vibration amplitude command means (not shown) with the detection result of the amplitude detecting unit 15 (amplitude velocity of the vibrating body). The power supply control unit 17 outputs at least one command of frequency, pulse width, and voltage amplitude to the voltage generating unit 41 according to the comparison result.

[0052] Generally, vibration actuators have variations or fluctuations in resonance frequency and internal loss due to manufacturing variations in friction members and pressure variations caused by the flatness accuracy of the vibrating body. It is difficult to uniform the vibration characteristics of multiple vibration actuators because there are also changes according to the rotation angle and changes caused by the progression of wear over time. However, in this embodiment, by adopting the above-mentioned configuration, the amplitude characteristics of each vibrating body are uniform, and a relatively uniform force can be transmitted to the bevel gear 31, resulting in less wear on the gears and efficient driving.

[0053] In the example of FIG. 15, the vibration actuator 42 does not include the inductors 37 and 39 and the capacitors 38 and 40, but some or all of the components may be included in the vibration actuator 42. The vibration actuator 42 includes components that are frequency matched according to their inherent resonant frequencies, making adjustments unnecessary when using the vibration actuator 42. This improves the convenience of the user who uses the vibration actuator 42 and reduces performance variations. In the example of FIG. 15, the inductor 37 and the capacitor 38 form a series resonant circuit, but only one of them may be connected to the vibration actuator 42. Similarly, only one of the inductor 39 and the capacitor 40 may be connected to the vibration actuator 42. The capacitor is used to block DC current, and the inductor has the effect of smoothing the waveform.

[0054] In addition, in this embodiment, the three vibration type actuators 18, 25, 28 are connected in series and coupled by the bevel gear 31 as a single vibration type actuator 42. Here, the vibration type actuator 42 consisting of the three vibration type actuators 18, 25, 28 can be used as a single vibration body unit, and a configuration in which multiple similar vibration body units are connected in series or in parallel can be adopted. This allows for the configuration of a vibration type actuator with even higher output. In this case, it is preferable to select the average values ​​of the resonance frequencies of the multiple vibration bodies contained in each vibration body unit so that they are approximately equal to each other. In addition, as a method for mechanically coupling the above multiple vibration body units, there is a method of coupling multiple composite vibration type actuators as shown in FIG. 11 with multiple gears equivalent to the bevel gear 31 coupled to the same shaft, or a method of coupling via other gears.

[0055] In the second embodiment, the three vibration actuators 18, 25, and 28 connected in series in the vibration unit may drive different contact bodies instead of one shaft (contact body). For example, a plurality of vibration actuators can be applied to applications where it is not necessary to move the contact bodies synchronously, such as when moving a plurality of dolls (contact bodies) displayed in a show window. In this case, it is effective because the plurality of vibration actuators can be stably driven at a moderate speed. For example, different dolls can be attached instead of the bevel gears 20, 27, and 30 in FIG. 11. In this case, by connecting the three vibration actuators in series equivalently, the three dolls can be rotated at approximately the same speed. In addition, by changing the winding ratio of the transformers of the three vibration actuators 18, 25, and 28, the three dolls can be rotated at different rotation speeds. For example, by setting the winding ratio of the transformers of the three vibration actuators 18, 25, and 28 to be proportional to the reciprocal of the ratio of the rotation speeds of the three dolls, the ratio of the rotation speeds of the three dolls can be set arbitrarily.

[0056] <Third embodiment> Next, the third embodiment will be described. FIG. 16 is a diagram showing the configuration and vibration mode of the vibrator of the third embodiment. FIG. 16(a) shows the configuration of the vibrator. The vibrator 43 is a plate-shaped vibrator made of a conductive material. Two protrusions that contact the contact body are provided on the surface of the vibrator 43. The piezoelectric body 47 constitutes a part of the vibrator 43 and vibrates the vibrator 43. FIG. 16(b) shows electrodes provided on the piezoelectric body 47, and the electrodes 48 and 49 are electrically insulated from each other. Two AC voltages whose phases change independently are applied to the electrodes 48 and 49. The entire back surface of the piezoelectric body 47 is an electrode, and is configured to be able to pass electricity from the front surface through vias (not shown) provided in parts of the electrodes 48 and 49.

[0057] FIG. 16(c) shows the vibration form of the vibration mode excited when the in-phase AC voltage is applied to the electrodes 48 and 49. FIG. 19(d) shows the vibration form of the vibration mode excited when the opposite-phase AC voltage is applied to the electrodes 48 and 49. When the phase difference between the AC voltages applied to the electrodes 48 and 49 is 0°, the vibration mode of FIG. 16(c) is excited. When the phase difference between the AC voltages applied to the electrodes 48 and 49 is 180°, the vibration mode of FIG. 16(d) is excited. When the phase difference between the AC voltages is between 0° and 180°, both vibration modes are excited simultaneously. In many cases, the phase difference between the AC voltages is about 0° to 120°. Then, the contact body that is in pressure contact with the protrusions provided on the vibrating body 43 moves. When the contact body is a rectangular parallelepiped, the contact body that is in pressure contact with the protrusions provided on the vibrating body 43 moves in the longitudinal direction of the rectangle.

[0058] Fig. 17 is a diagram showing an example of a vibration type actuator of the third embodiment. In Fig. 17, three vibrating bodies 43, 44, and 45 are evenly arranged along a circular contact body 46. The circular contact body 46 is rotatably held by a support member (not shown). The three vibrating bodies 43, 44, and 45 are excited to vibrate, so that the contact body 46 can be rotated.

[0059] FIG. 18 is a diagram showing an example of a drive circuit of a vibration type actuator of the third embodiment. In the vibrating body 43, the secondary coil of the transformer 53 is connected in parallel to the A-phase side, and the secondary coil of the transformer 54 is connected in parallel to the B-phase side. A capacitor for finely adjusting frequency matching is connected in parallel between each of the transformers 53, 54 and the vibrating body 43. The vibrating bodies 44, 45 have the same configuration as the vibrating body 43. The primary coils of each transformer are connected in series for each phase. That is, the primary coils of the transformers 53, 55, 57 on the A-phase side are connected in series. In addition, the primary coils of the transformers 54, 56, 58 on the B-phase side are connected in series. Both ends of the transformers 53, 55, 57 connected in series are connected to the H-bridge of the voltage generating unit 41 via a series resonant circuit formed by the inductor 37 and the capacitor 38. In addition, both ends of the transformers 54, 56, 58 connected in series are connected to the H-bridge of the voltage generating unit 41 via a series resonant circuit formed by the inductor 39 and the capacitor 40. The series resonant circuit may include either an inductor or a capacitor, or may include both.

[0060] Moreover, the voltage generating unit 41 outputs a four-phase pulse signal whose phase differs every 90°. The driving circuit of the vibration type actuator shown in FIG. 18 has a torque detecting unit 50. The torque detecting unit 50 detects the torque on the contact body 46. The torque detecting unit 50 outputs the detected torque to the comparing unit 51. The comparing unit 51 compares the torque detected by the torque detecting unit 50 with a torque command from a command means (not shown) and outputs the comparison result to the vibration amplitude commanding unit 52. The vibration amplitude commanding unit 52 controls the vibration amplitude of the vibrating bodies 43, 44, and 45 according to the comparison result output by the comparing unit 51. Furthermore, resistors 14 and 36 for measuring current are connected to the source terminals for current detection of each H-bridge of the voltage generating unit 41. The resistors 14 and 36 detect the current according to the vibration speed of the vibrating bodies 43, 44, and 45. The amplitude detecting unit 15 detects the vibration amplitude from the current detection result. The comparison unit 16 compares the detected vibration amplitude with the vibration amplitude command output by the vibration amplitude command unit 52, and outputs the comparison result to the voltage generation unit 41. The power supply control unit 17 controls at least one of the frequency, the pulse width, and the voltage amplitude of the voltage generation unit 41 according to the comparison result.

[0061] Here, for example, when the torque to the contact body 46 is smaller than the target value, the frequency of the AC voltage output by the voltage generating unit 41 approaches the resonant frequency of the vibrating bodies 43, 44, and 45, and the vibration amplitude of the vibrating bodies 43, 44, and 45 increases. This increases the torque to the contact body 46. Also, a configuration can be adopted in which the torque detecting unit 50 is a speed detecting unit that detects the speed of the contact body 46, and the comparing unit 51 compares the detected speed with a speed command from a command means (not shown). This makes it possible to control the moving speed of the contact body 46.

[0062] Fig. 19 is a diagram showing a first example of a linear vibration type actuator of the third embodiment. Fig. 19(a) is a diagram seen from a direction perpendicular to the movement direction of the contact body 70. The protrusions of the two vibrating bodies 43, 44 are arranged facing each other, and the contact body 70 is configured to move in the direction of the arrow in Fig. 19(a) with the contact body 70 sandwiched between them from above and below. Fig. 19(b) is a diagram seen from the movement direction of the contact body 70, in which the vibrating bodies 43, 44 are arranged symmetrically above and below the contact body 70 (evenly spaced at 180° intervals around the circumference).

[0063] FIG. 20 is a diagram showing a second example of the linear vibration type actuator of the third embodiment. In FIG. 20, the contact body is a prism with a square cross section, and the protrusions of the vibrator apply pressure from four sides toward the prism-shaped contact body. FIG. 20(a) is a diagram seen from a direction perpendicular to the moving direction of the contact body 71. FIG. 20(b) is a diagram seen from the moving direction of the contact body 71. As shown in FIGS. 20(a) and (b), four vibrators 43, 44, 61, and 62 are evenly arranged at 90° intervals around the center of the contact body 71, which is a prism with a square cross section. The vibrators 43, 44, 61, and 62 have two electrodes (not shown) provided on the piezoelectric body of each vibrator, which are equivalently connected in series via a transformer for each phase of the applied AC voltage. A transformer is connected in parallel to each vibrator, similarly to the vibrators 43, 44, and 45 in FIG. 18.

[0064] Although the contact body in FIG. 20 is an example of a prism with a square cross section, the contact body may be a cylinder with a circular cross section. Also, FIG. 20 shows an example in which four vibrators are treated as one vibrator unit and the four vibrators are equivalently connected in series via a transformer. In this regard, a configuration in which two vibrators facing the contact body are treated as one vibrator unit and the two vibrator units are connected in series or in parallel may be adopted. Also, a configuration in which the four vibrators in FIG. 20 are treated as one vibrator unit and multiple vibrator units are arranged along the moving direction of the contact body 71 and each vibrator unit is connected in parallel or in series may be adopted. Furthermore, multiple vibrators may drive different contact bodies. Also, multiple vibrators may be divided into a predetermined number of groups, and different contact bodies may be driven for each divided group.

[0065] <Fourth embodiment> Next, the fourth embodiment will be described. FIG. 21 is a diagram showing a first example of a vibration type actuator of the fourth embodiment. In FIG. 21, two of the vibrating bodies 61 and 63 and two of the vibrating bodies 62 and 64 constitute one vibrating body unit. The vibrating bodies 61 and 63 constitute a Y-axis vibrating body unit that drives the contact body 65 in the Y-axis direction. The vibrating bodies 61 and 63 are equivalently connected in series via a transformer. The vibrating bodies 62 and 64 constitute an X-axis vibrating body unit that drives the contact body 65 in the X-axis direction. The vibrating bodies 62 and 64 are equivalently connected in series via a transformer. The resonance frequency of the X-axis vibrating body unit and the resonance frequency of the Y-axis vibrating body unit are sufficiently separated so as not to affect each other, and the shape of each vibrating body is adjusted so that the driving frequency ranges do not overlap.

[0066] FIG. 22 is a diagram showing a first example of a drive circuit of a vibration type actuator of the fourth embodiment. Vibrators 61 and 63, which are the Y-axis vibrator unit, and vibrators 62 and 64, which are the X-axis vibrator unit, are equivalently connected in series via a transformer for each phase. A capacitor is connected in parallel to each vibrator. The inductance of the secondary coil of the transformer and the value of the capacitor, including the damping capacity of each vibrator, are frequency-matched to the Y-axis frequency Fy for the Y-axis vibrator unit and to the X-axis frequency Fx for the X-axis vibrator unit. FIG. 23 is a diagram showing the vibration characteristics of each vibrator unit of the fourth embodiment. The solid line shows the vibration characteristics of the X-axis vibrator unit, and the dashed line shows the vibration characteristics of the Y-axis vibrator unit. As shown in FIG. 23, the X-axis vibrator unit has a drive frequency range on the high frequency side of the frequency of the maximum amplitude (maximum value of the vibration amplitude). And the X-axis frequency Fx is set within the drive frequency range. Similarly, the Y-axis vibrator unit also has a drive frequency range on the high frequency side of the frequency of the maximum amplitude. The Y-axis frequency Fx is set within this drive frequency range.

[0067] The voltage generating unit 69 synthesizes AC voltages in two frequency ranges including the X-axis frequency Fx and the Y-axis frequency Fy. The voltage generating unit 69 generates two-phase AC voltages in each frequency range. Capacitors 38 and 40 are inserted between the voltage generating unit 69 and each vibrating body unit. This blocks the DC current. As shown in FIG. 22, the driving circuit of the vibration type actuator has an amplitude detecting unit 66. A sum signal of two-phase currents flowing according to the vibration speed of each vibrating body detected by the current detection resistor 14 is input to the amplitude detecting unit 66. The amplitude detecting unit 66 detects the vibration amplitude for each frequency range of the X-axis driving frequency range and the Y-axis driving frequency range based on the input sum signal. The comparing units 16 and 67 compare the detected vibration amplitude with the X-axis amplitude command and the Y-axis amplitude command from the command means (not shown) and output the comparison result to the power supply control units 17 and 68. Based on the comparison result, the power supply control units 17 and 68 control the frequency of the AC voltage applied to the X-axis vibration body unit and the Y-axis vibration body unit.

[0068] In addition, a command means (not shown) monitors the output of a two-dimensional position detection means (not shown) and compares it with the target position of each axis. Then, the command means (not shown) switches the X-axis phase and the Y-axis phase to "90°" or "-90°" according to the sign of the comparison result, and sets the X-axis amplitude command and the Y-axis amplitude command according to the absolute value of the comparison result. Methods for separating signals in two frequency ranges include a method of separating using a filter, a method of obtaining frequency and amplitude by FFT calculation, and a method of performing synchronous detection of a synchronization signal generated by the voltage generating unit 69. In addition, when detecting the vibration speeds of the X-axis vibrator unit and the Y-axis vibrator unit from the sum of currents, simply separating the frequencies generates errors in the measurement of the amplitude. Therefore, an offset value of the amplitude for each frequency obtained in advance is set in the amplitude detection unit 66, and a correction calculation is performed based on the offset value for the obtained amplitude and frequency information, thereby making it possible to detect the vibration speed with high accuracy.

[0069] 24 is a diagram showing a second example of a drive circuit for the vibration actuator of the fourth embodiment. For each vibrator unit having a different drive frequency range, a series circuit made of an inductor and a capacitor that match at a predetermined frequency within the respective drive frequency range is inserted between the voltage generating unit 69. By inserting a series circuit made of an inductor and a capacitor, distortion of the voltage waveform applied to each vibrator unit is reduced.

[0070] FIG. 25 is a diagram showing a second example of the vibration type actuator of the fourth embodiment. In FIG. 25, the vibration body units 72, 73, 74, 75, and 76 have a plurality of vibration bodies and a plurality of transformers. Each vibration body is connected to a secondary coil of the transformer, and the primary coil of each transformer is connected in series. Therefore, as described above, each vibration body is equivalently connected in series. The vibration body units 72, 73, 74, 75, and 76 are each configured to have a vibration body whose driving frequency range does not overlap. The vibration body units 72, 73, 74, 75, and 76 are electrically connected in parallel and driven by two-phase AC voltages PA and PB. The vibration body units 72, 73, 74, 75, and 76 sandwich a linearly moving contact body between a plurality of vibration bodies equivalently connected in series as shown in FIG. 19 or FIG. 20, and a wire bundle 77 is coupled to the contact body.

[0071] The wire bundle 77 is engaged with a tube-shaped bending driver 78 that resembles a finger, and is configured so that multiple pseudo joints of the bending driver 78 can be bent and stretched by pushing and pulling each wire of the wire bundle 77. One wire of the wire bundle 79 corresponds to the vibration body units 72, 73, 74, 75, and 76. By linearly moving the contact body contained in the vibration body units 72, 73, 74, 75, and 76, the bending driver 78 can be driven to bend and stretch a finger. Therefore, since multiple axes can be driven with a small number of wires, it is effective when driving a complex robot hand having multiple joints. When the vibration type actuator of this embodiment is applied to a mechanism that moves multiple different parts, such as a robot hand, the thrust required for each vibration body unit may differ. In such a case, the winding ratio of the transformer connected to each vibration body may be set to a different value so that the required thrust can be obtained.

[0072] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0073] 1, 2, 3 Vibration body 4 Cylindrical Shaft 5, 6, 7 Transformers 10, 11 Vibration unit 13 Voltage generation section 14 Resistance 15 Amplitude detection section 16 Comparison section 17 Power supply control section 23 Piezoelectric

Claims

1. A vibration actuator including a vibration body unit and a contact body, The vibrating body unit includes: a first vibrating body having a first electromechanical energy conversion element and a first elastic body; a second vibrating body having a second electromechanical energy conversion element and a second elastic body; a first transformer to which the first vibrating body is connected; a second transformer to which the second vibrating body is connected; At least a primary coil of the first transformer and a primary coil of the second transformer are connected in series, and the first vibrating body and the second vibrating body are connected in parallel to the secondary coil of the first transformer and the secondary coil of the second transformer, respectively; The first elastic body and the second elastic body are arranged at an interval, A vibration actuator characterized in that the first vibrating body and the second vibrating body are in contact with a common contact body, and vibration of the first vibrating body and the second vibrating body causes relative movement between the vibrating body unit and the contact body.

2. 2. The vibration actuator according to claim 1, wherein a capacitor is connected in parallel to each of the first vibrating body and the second vibrating body.

3. 3. The vibration actuator according to claim 1, wherein the inductance values ​​of the secondary coil of the first transformer and the secondary coil of the second transformer are matched at a frequency within a predetermined range from the resonant frequency of the vibrating body unit.

4. 4. The vibration actuator according to claim 3, wherein an average value of the resonance frequencies of the first vibrating body and the second vibrating body is within a predetermined frequency range.

5. 4. The vibration actuator according to claim 3, wherein a dispersion of the resonance frequencies of the first vibrating body and the second vibrating body is within a predetermined dispersion range.

6. 6. The vibration actuator according to claim 1, wherein the first transformer and a part or all of the second transformer have different winding ratios.

7. 7. The vibration actuator according to claim 1, wherein a plurality of the vibrating body units are connected in parallel.

8. 8. The vibration actuator according to claim 1, wherein the first transformer and the second transformer of some or all of the plurality of vibration body units have different winding ratios.

9. 9. The vibration actuator according to claim 1, wherein the driving frequency ranges of the plurality of vibrating body units do not overlap with each other.

10. The vibration actuator according to any one of claims 1 to 9, characterized in that the vibration body unit has the first vibration body and the second vibration body having a plurality of vibration sections each having a different phase of an input AC voltage, and the plurality of vibration sections of the first vibration body and the second vibration body are connected to secondary coils of the first transformer and the second transformer for different phases.

11. The vibration actuator according to claim 10, characterized in that the plurality of vibration sections have a plurality of sections groups that are 180° out of phase with each other, and each section group is connected to the secondary coils of the first transformer and the second transformer.

12. 2. The vibration actuator according to claim 1, wherein an inductor and / or a capacitor are connected to the primary coil of the first transformer and the primary coil of the second transformer, which are connected in series.

13. A driving device for a vibration type actuator that drives the vibration type actuator according to any one of claims 1 to 12, comprising: a voltage generating unit that generates an AC voltage to be applied to the vibration body unit; an amplitude detection unit that detects the amplitude of an AC voltage from a current flowing through the vibrator unit; a power supply control unit that controls the AC voltage generated by the voltage generating unit based on the amplitude of the current detected by the amplitude detecting unit; A driving device for a vibration type actuator comprising:

14. 14. The driving device for a vibration type actuator according to claim 13, wherein the amplitude detection section detects that a failure has occurred in the vibrating body unit when the increase in the current is equal to or greater than a predetermined amount.

15. A torque detection unit that detects a torque applied to the contact body, 15. The driving device for a vibration actuator according to claim 13, wherein the power supply control unit controls the AC voltage generated by the voltage generating unit based on the detected torque and the amplitude of the current.

16. the voltage generating unit generates an AC voltage obtained by combining a plurality of AC voltages in different frequency ranges; the amplitude detection unit detects the amplitude of the current for each of the different frequency ranges; 16. The driving device for a vibration type actuator according to claim 13, wherein the power supply control unit controls the AC voltage generated by the voltage generating unit for each of the different frequency ranges.

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